Conventionally, the stand-up packaging pouch which includes a rib in a pinch form formed by adhering inner faces of end edges of a packaging material and on which at least one pleat extends in the direction orthogonal to its longitudinal direction has been used. In the conventional stand-up packaging pouch, edges are formed between a folded bottom portion and front, rear, and side face portions, and the pleat extends in the same plane as the front, rear, and side faces (refer to the patent publication 1).
Further, in the conventional stand-up packaging pouch, the pleat is formed at its lower end by folding it in a three-ply strip form and applying a heat seal to the folded inner faces to conceal its bottom face portion. This causes the hermetical pleat with no wrinkles to be obtained.
However, as shown in FIG. 10, in the packaging material which includes a rib in a pinch form formed by adhering inner faces of its end edges, there was a technical problem that it is difficult to apply a heat seal to a cross portion between the rib and the pleat which is positioned orthogonal thereto and to sharply bend the cross section. In FIG. 10(a), the rib 71 is formed in a pinch form by adhering inner faces of end edges of the packaging material 70. In addition, at least one pleat 72 is formed by folding the packaging material 70 in a three-ply strip form in the direction orthogonal to its longitudinal direction and adhering the folded inner portions. As shown in FIGS. 10(a) and 10(b), the rib 71 is inclined in one direction. The portion 73 where the rib 71 and the pleat 72 cross is formed. As shown in FIG. 10(c), the cross portion 73 is positioned to be edges between a bottom face portion and an outer peripheral portion in a case where the packaging material 70 is folded in order to form the bottom face portion on its lower end. FIG. 10(c) shows a situation in which the plane packaging pouch is formed into a packaging body in a three dimensional form.
There are two technical problems with respect to the packaging body in FIG. 10(c).
Firstly, the heat seal can be imperfect due to the crossed rib. Such technical problem is explained with reference to FIG. 11 (b). FIG. 11 (b) shows a cross section at the cross portion 73 where the rib 71 and the pleat 72 cross, more specifically, a cross section along with X(b)-X(b) in FIG. 10(c). The reference numbers 72a to 72f indicate pleats, and the inner faces of the pleats 72a and 72b, the inner faces of the pleats 72c and 72d, and the inner faces of the pleats 72e and 72f, are heat sealed, respectively. The inner faces of the rib 71a and 71b are heat sealed in a pinch form to form a rib. In a case where the end edges of the packaging material are heat sealed in a pinch form after the pleat is formed by the heat seal, the side of the rib 71a are heat sealed from above the pleats 72a and 72b, while the side of the rib 71b are heat sealed from above the pleats 72c and 72d. In general, the heat seal is applied in such a way that an outer face of the packaging material is pressed by a heated heat sealer. In a case where the ribs 71a and 71b are heat sealed, the pleats 72a and 72b, and the pleats 72c and 72d are positioned so as to sandwich the ribs 71a and 71b in a pinch form, whereby the heat transmission from the heat sealer to the ribs 71a and 71b can be blocked. If the heat seal is applied in such a situation, the heat seal can be imperfect due to the fact that the heat transmission from the heat sealer only to the cross portion 73 where the rib 71 and the pleat 72 cross can be insufficient.
Secondly, the lower end of the packaging material 70 is bent in order to form the bottom face portion and the pleat is positioned to be the edge between the bottom face portion and the outer peripheral portion. The rib is formed by substantially laminating a plurality sheets of the packaging material, since the pleats where two sheets of the packaging material are substantially laminated are adhered in a pinch form at the bent portion. In a case where the bottom of the packaging material is formed, it is necessary to fold the rib at a substantially right angle. In such a case, seven sheets of the packaging material are laminated at the bent portion, since the rib is bent in either right or left direction to be inclined. As shown in FIG. 11(b) showing the cross section of the bent portion, the seven sheets 71a, 71b, 72c,72d,72e,72f, and 74 of the packaging material are folded. More specifically, the ribs 71a and 71b press the pleats 72c, 72d, 72e and 72f from outside (FIG. 11(b)), so that the pleats 72c,72d,72e and 72f are forced to be curved, and as a result, a stability and an aesthetic appearance are worsened.
The patent publication: Japanese Patent Laid-open Publication 2003-191963